Non-suicidal self-injury (NSSI), defined as the direct, intentional destruction of one's own body tissue without the intent to die (1), is more common than once believed; approximately 14% to 35% of college students (2,3) engage in the behavior. Additionally, NSSI is associated with numerous adverse outcomes, including tissue damage/scarring, disruptions in interpersonal relationships, and future suicidal behavior (4-10). Although research on NSSI is increasing, most studies continue to use non-experimental methods that limit our ability to examine causal relationship between NSSI and its correlates. The inclusion of behavioral paradigms would allow for empirical investigations of NSSI in a way that mimics real-life behavior, providing richer information about NSSI behavior and putatively related variables. One such variable of interest is interpersonal stress, which is thought to have a substantial impact on self-injurious thoughts and behaviors. For example, interpersonal problems have been found to precipitate self-harming thoughts (28) and more severe self-harming behaviors (e.g., suicide attempts; 29-31). There is little empirical evidence, however, examining the immediate impact of interpersonal stress on NSSI, and related potential deficits, such as interpersonal problem solving abilities (32). The proposed study will experimentally examine the effect of interpersonally-focused acute negative mood on self-injurious behavior/attitudes, and interpersonal problem solving. Given the high rate of NSSI among college-aged individuals, the participants of the proposed study will be college students with and without a recent history of NSSI. Participants will complete a diagnostic assessment and self-report measures of constructs related to self-injurious behavior. Following, they will receive either (a) an interpersonal negative mood induction (b) a general negative mood induction or (c) an interpersonal neutral mood induction, after which they will complete behavioral measures of interpersonal problem solving, self-injurious behavior, and implicit NSSI associations. The multi-group, multi-method design of this study will allow for a powerful assessment and comparison of the specific impact of an interpersonally- focused negative mood on NSSI behaviors. Thus, this study has the potential to provide a better understanding of the emotional and behavioral responses to acute negative mood and could provide new insights into extant theories of self-injury and may help guide NSSI treatment and prevention efforts.